Moderate to dense fog was witnessed in parts of Delhi on Saturday morning, even as visibility improved in several areas, according to the India Meteorological Department (IMD).

The visibility was 200 metres at Safdarjung, Delhi's main weather station, and 500 metres at Ridge.

According to an advisory issued by the IMD for Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, north Rajasthan and north Madhya Pradesh, fog may affect visibility at some airports, highways and railway routes.

Train services were impacted due to fog for the fourth straight day with 30 Delhi-bound trains delayed.

The minimum temperature in Delhi was recorded at 11.8 degrees Celsius, five notches above the season's average, IMD said.

The relative humidity stood at 88 per cent at 8:30 am.

Delhi Air Quality Index (AQI) was recorded at 399, in the 'very poor' category, at 8 am.

An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.

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